Performance and shower shape studies with EPICAL-2

Abstract

A prototype of a novel digital electromagnetic calorimeter, EPICAL-2, has been developed. The R&D is performed in the context of the ALICE-FoCal and is closely related to studies of imaging in proton CT. Digital calorimetry also proves promising for future collider projects such as EIC, ILC, CLIC, or FCC. Based on a proof-of-principle with a first prototype, EPICAL-2 has been constructed as an advanced second prototype. EPICAL-2 consists of 24 layers with alternating tungsten absorbers and ALPIDE MAPS. The design features an active area of approximately 27x30mm2 and a depth of 20 radiation lengths, totaling over 25 million pixels. EPICAL-2 test-beam measurements were performed at DESY in February 2020 and CERN-SPS in September 2021. Simulations of the EPICAL-2 detector have been carried out with the Allpix2 framework. Performance studies with EPICAL-2 show promising energy response and resolution. Beyond its main calorimetric abilities, EPICAL-2 allows for detailed shower shape studies. Measurements of the longitudinal and lateral shower shape and the Molière radius have been carried out, indicating strong shower separation power of the EPICAL-2’s design.